Larry Zapp was morbidly obese (around 400 pounds) and nearly incapable of walking.
Larry Zapp, aka Boss Larry, as he liked to be called, was the baron of Greenglades and a technical genius. He started out running a mobile gaudy house, but ran afoul of Trader, who had Ryan and JB beat him badly. He recovered and moved south to Florida, where he found the old Greenglades Amusement Park and fixed it up. He renovated a nearby prison into housing for old people, taking their money in exchange for a safe place to live.
After his wife died, he fell into a deep depression, which made him vulnerable; when Adam Traven came to town with his posse, he got Larry hooked on dreem and slowly began to wrest power from him. During the final confrontation between Adam and the companions, Larry fell on top of Adam, pinning him, but Adam shot him several times and he died (Dark Carnival).
Baron Zapp once referred to JB Dix as John Dix, this could have been a typo or perhaps one of his previous employees had gotten to know the Armourer much better than most, as he always kept his name a secret.